Combination pad and insulator for cushions



May 23, 1961 1.. J. STERN COMBINATION PAD AND INSULATOR FOR CUSHIONS Filed June 11, 1957 INVENTOR (EM l5 1/; STEP/V man Maw ATTORNEY COMBINATION PAD AND INSULATOR FOR CUSHIONS Lewis J. Stern, Adrian, Mich., assignor to Stubnitz Greene Corporation, Adrian, Mich., a corporation of Michigan Filed June 1'1, 1957, Ser. No. 664,947

1 Claim. (Cl. 155-181) nited States Patent either transverse or longitudinal in direction depending upon the final properties desired. When chopped fiberous material is used for the insulator strip, the physical properties thereof may be varied by controlling the location and orientation of the strands or by slitting the molded chopped fibers in longitudinal, transverse or angular directions.

It is also within the scope of the present invention to mold the pad and then bond the insulator strip to the pad as a separate operation. Moreover, it is contemplated that the pad and insulator strip may be molded together and the resulting pad may have a further pad portion applied thereto. For example, a pad portion of polyester-urethane foam material may be integrally attached to a burlap insulating strip as one operation and,

- thereafter, the resulting pad may have applied to its upper insulating strip disposed directly over the top of the spring :1

elements defining the resilient supporting structure of the seat. The function of this insulating strip was to protect the pad material disposed above the spring elements from the abrading action of the spring elements and to distribute the support of the spring elements over the entire area of the pad material and avoid the possibility of the outline of the spring elements being felt by a person sitting upon the upholstered seat. One form of insulating strip of the type just described is shownin Patent No.

According to the present invention it is proposed to substitute for known forms of pad and insulator strips, an improved seat pad construction in which a molded reaction material has associated therewith, as an integral bonded part, an insulator pad or strip, In carrying out the invention, I have provided an improved method whereby the foam material is molded with the insulator pad or strip in place and the foam pad and insulator strip.

are bondedtogether as an integral laminated unit.

Preferably my improved integral pad and insulator strip is molded with retaining grooves to enable the pad to be snapped over the top border frame of the spring structure with the elimination of other known forms ofattachment structure for such pads, as for example hog rings and the like, for retaining the pad in position before applying the final trim. Preferably the'material of the insulating strip is disposed withinthe retaining grooves of the pad to reinforce that area. I

The insulating strip materialto be integrally molded in the pad may bev burlap, cotton, linen, felt, jute, paper, sisal or other suitable material in woven or so-called weftless form. The insulator strip may also be formed of string, cord, rope, wire net or screening. Moreover, the insulator strip may comprise chopped fibers such as glass fibers, of diiferent length, roving and the like, blown or otherwise positioned within the mold and then molded into position. y

If woven or meshed material is used for the integral insulator strip, it is possible to vary the physical properties of the insulator strip by means of slits cut in the strip either before or after molding. These slits may besurface a pad section of polyether-urethane foam material.

Thus, an object of the invention is to provide an improved snap-on pad for spring structures.

Another object of the invention resides in the provision of an improved pad for spring structures in which the surface of the pad to be adjacent the spring elements is reinforced by an insulating strip fixed to the pad surface and having areas severed from each other.

A further object is to provide a pad for upholstering spring structure having foam sections of difierent consistency.

A still further object of the invention is to provide an insulator strip and foamed pad being in the form of lon- 'ij gitudinally extending narrow sections separated from each other and integrally bonded to the foamed pad.

' These and other objects and advantages of the invention will more fully appear from the'following description and the appended claim. a a a In the drawings, a Fig. 1 is a diagrammatic cross-sectional showing of my improved pad supported upon spring elements,

Fig. 2 is an enlarged view of a detail shown in Fig. 1, Fig. 3 is an enlarged fragmentary perspective view of a pad showing the insulator strip of slitted form,

Fig. 4 is a diagrammatic sectional view of'a mold for carrying out the method of the invention, and I Fig. 5 is a fragmentary view similar to Fig. 1 showing a pad of sectional foamed structure.

In the illustrated form of the invention shown in Figs.

- l and 2, the molded foam pad 10 has a retaining groove- 12 adapted to receive the upper border frame 14 of the spring structure 16. Located at the underside of the pad 10 in a position to engage directly with the spring structure 16 is an insulator strip 18 which is suitably bonded or otherwise integrally associated with the surface of the pad 10 which is engaged by the spring elements 20.

In practice, the strip 18 may be of light weight woven burlap or cotton canvas. When the strip 18 is to be molded integrally withthe pad 10, the strip 18 may be placed in a suitable mold 22, as shown in Fig. 4. 1 By making the mold 22 in the manner shown, the strip 18 may be clamped in position within the mold and, thereafter, when the reaction material 24 is placed in the mold and the chemical foaming action takes place to fill the mold 22 the reaction material penetrates the interstices of thestrip 18 to integrally bond the same to the pad 10 upon curing the material within the mold in a well known manner. Upon removing the pad 10 from the mold, the strip 18 may 'be severed to provide slits 25. Fig. 5 shows a pad 10' having a very soft upper part 26 of foamed material and a lower part 28 of a somewhat more firm foamed material, the latter being bonded to the insulator strip 18. The upper part 26 may be separately formed and then bonded to the part 28 or it may be foamed and cured on the lower part 28 as a separate operation from the foaming and curing of the lower part 28. It will be understood that any suitable bonding or adhesive material compatible with the foam reaction material may be employed to secure the sections 26 and 28 together or to attach the insulator strips 18 and 18 in position Where they are not integrally bonded by impregnation of foamed material taking place in the mold itself.

The narrow rectangular portions which are formed from the insulator 18 by the slits 25 are only connected to each other indirectly through the body of the foam constituting the pad By this arrangement, these narrow portions are still capable of presenting a relatively solid surface to the spring structure 16 yet are capable of relative movement to each other along the lines between the contiguous longitudinal edges of adjacent narrow portions formed by the slits 25.

The reaction material which is preferably formed and cured in bonding relation to the insulating strip material 18 and 18 may take several forms depending upon the results desired. Using polyester-urethane foams, for a 25% deflection, a compression resistance in the range of 0.8 to 1.2 pounds per square inch has been obtained. With polyether-urethane foams, for a 25% deflection, a compression resistance in the range of 0.2 to 0.5 pound per square inch has been obtained. To insulate against the feel of the spring structure 16, the polyester type foams permit the use of relatively thin pads. However, the insulating strip 18 reduces the thickness and density requirements of the foam layer or layers of the pad 10 and contributes to the economy of the composite seat construction. It also increases the serviceability of the foam material making up the main body of the pad 10.

An example of a suitable type of polyester foam follows:

Parts by weight Resin 100.0 Emulsifier 1.0 to 2.0 Catalyst 0.1 to 2.0 Water 1.5 to 4.0 Diisocyanate 20.0 to 55.0

In the above example, the resin would be saturated polyester resin having a low acid number, preferably less than 2.0 and a hydroxyl number of 60 plus or minus 15. The emulsifier may be anionic or a mixture of anionic and a non-ionic detergent. The catalyst is a tertiary amine and preferably N-methyl morpholine. The water may be distilled or deionized or mere tap water although preferably it is distilled or deionized. 'I he diisocyanate is an isomeric mixture of 2,4-tolylene diisocyanate and 2,6- tolylene diisocyanate of which the ratio of isomers lies between 65 and 80 parts of the 2,4-iso-mer to 35 and 20 of the 2,6-isomer. The 80 20 isomeric mixture is preferable wherein the 80 parts is the 2,4-isomer.

A specific formula used in practice and falling within the above example is:

Parts by weight Resin 100.0 Witco 77-86 2.0 N-methyl rnorpholine 1.0 Water 3.0

Hylene TM 43.0

droxyl groups in the resin are converted to urethane groups by using a large excess of diisocyanate. Thus, all the functional groups of the prepolymer are isocyanate. This prepolymer is then used as one of the components and the second component consists of additional resin, emulsifier, catalyst and water. For example, the first component may consist of resin 50 parts by weight and diisocyanate 43 parts by weight and the second component may consist of resin 50 parts by weight, emulsifier 2 parts by weight, catalyst one part by weight and water 3 parts by weight. The reaction of the first and second components produces the foam.

An example of a suitable type of polyether-urethane foam follows: The polyether foams involve the prepolymer system only. The usual practice is to combine the resin with an excess of diisocyanate to form the prepolymer. The isocyanate groups which are not reacted in the formation of the prepolymer are free to react with water in producing the foam. In like manner, such free isocyanate groups may react with other materials containing active hydrogen compounds, e.g., burlap, cotton, etc. For example, the block polymer Tetronic 701 which is a condensate of ethylene oxide, propylene oxide and ethylene diamine is cooked with tolylene diisocyanate 20 isomer mixture). The resulting resin is converted to a foam by mixing with an emulsifier, catalyst and water. A typical formulation is as follows:

Prepolymer:

Parts by weight Tetronic 701 100.0 Hylene TM 34.8 Cook two hours at F. to form prepolymer.

Foam formulation:

Parts by weight Prepolymer 100.0 DC-200 (50 centistokes) 0.5 N-methyl morpholine 1.0 Water 2.8 Triethylamine 0.2

The prepolymer may consist of a mixture of polymers including such resins as Pluronics, polypropylene glycol, Teracol, etc. Usually the mixed polymers'are mixed together and then cooked with diisocyanate rather than involving separate cooks with subsequent mixing.

Preferably the insulator strip is bonded to the cellular reaction product in the mold during the foaming action with the result that the physical characteristics of the insulator strip are improved by the impregnation of the foam material and the chemical reaction taking place between the reaction material and the insulator strip.

An important feature of the present invention resides in the concept of a resilient pad having a depending peripheral flange with a recess defined therein adapted to receive the upper border wire of the spring structure, the resilient character of the pad enabling the same to be snapped upon the upper border frame.

' In connection with the method of forming a laminated cellular reaction product especially designed for use as a pad, it is to be understood that the foam is allowed to expand against the insulating sheet of burlap or other fabric making up the insulator strip and the foam penetrates the porous fabric material becoming mechanically bonded thereto. As a result the fabric is stiffened. In addition, reaction of free diisocyanate in the foaming product with reactive groups in the fibrous material of the fabric (principally hydroxyl groups) vulcanizes the foamed reaction product to the fabric. This reaction results in further stifiening the fabric sheet and converts it into an excellent insulating strip bonded to the resilient cellular pad body and provides excellent high tear and abrasion resistance.

I claim:

A top pad for spring structure comprising a main body of resilient material having a relatively smooth regular surface portion directly adjacent the spring structure upon which the pad is to be supported, an insulating structure of flexible sheet material in contact with and bonded to the entire area of said surface portion to reinforce said surface portion and to distribute the support of the spring Structure to said main body, said insulating structure being in the form of elongated, narrow rectangular strips in parallel arrangement with the longitudinal edges of adjacent strips in contiguous relation to each other, the sole connection between adjacent said strips being an indirect connection constituted by the mutually bonded association of said strips with said body, said strips presenting a relatively solid surface to said spring structure yet being capable of movement relative to each other along lines between the contiguous longitudinal edges of adjacent strips.

References Cited in the file of this patent UNITED STATES PATENTS 920,256 Broadhurst et al May 4, 1909 1,843,893 Becher Feb. 2, 1932 2,783,827 Neely Mar. 5, 1957 FOREIGN PATENTS 745,747 Great Britain Feb. 29, 1956 

